package com.io.filter;

import com.io.constant.CommonConstant;
import com.io.utils.shiro.JwtToken;
import lombok.extern.slf4j.Slf4j;
import org.apache.shiro.web.filter.authc.BasicHttpAuthenticationFilter;
import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.RequestMethod;

import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * The class/interface
 *
 * @author guod
 * @version 1.0 use jdk 1.8
 */
@Slf4j
public class JwtFilter extends BasicHttpAuthenticationFilter {

    /**
     * 执行登录认证(判断请求头是否带上token)
     */
    @Override
    protected boolean isAccessAllowed(ServletRequest request, ServletResponse response, Object mappedValue) {
        // 检测headers里是否包含token字段
        if (isLoginAttempt(request, response)) {
            try {
                executeLogin(request, response);
            } catch (Exception e) {
                response401(response);
            }
            return true;
        } else {
            // 如果请求头不存在 token，则可能是执行登陆操作或者是游客状态访问，无需检查 token，直接返回 true
            response401(response);
            return false;
        }
    }

    /**
     * 判断用户是否是登入，检测headers里是否包含token字段
     */
    @Override
    protected boolean isLoginAttempt(ServletRequest request, ServletResponse response) {
        HttpServletRequest req = (HttpServletRequest) request;
        String authorization = req.getHeader(CommonConstant.ACCESS_TOKEN);
        return authorization != null;
    }

    /**
     * 重写AuthenticatingFilter的executeLogin方法丶执行登录操作
     */
    @Override
    protected boolean executeLogin(ServletRequest request, ServletResponse response) {
        HttpServletRequest httpServletRequest = (HttpServletRequest) request;
        // Access-Token
        String token = httpServletRequest.getHeader(CommonConstant.ACCESS_TOKEN);
        JwtToken jwtToken = new JwtToken(token);
        // 提交给realm进行登入,如果错误他会抛出异常并被捕获, 反之则代表登入成功，返回true
        getSubject(request, response).login(jwtToken);
        return true;
    }

    /**
     * 对跨域提供支持
     */
    @Override
    protected boolean preHandle(ServletRequest request, ServletResponse response) throws Exception {
        HttpServletRequest httpServletRequest = (HttpServletRequest) request;
        HttpServletResponse httpServletResponse = (HttpServletResponse) response;
        httpServletResponse.setHeader("Access-control-Allow-Origin", httpServletRequest.getHeader("Origin"));
        httpServletResponse.setHeader("Access-Control-Allow-Methods", "GET,POST,OPTIONS,PUT,DELETE");
        httpServletResponse.setHeader("Access-Control-Allow-Headers", httpServletRequest.getHeader("Access-Control-Request-Headers"));
        // 跨域时会首先发送一个option请求，这里我们给option请求直接返回正常状态
        if (httpServletRequest.getMethod().equals(RequestMethod.OPTIONS.name())) {
            httpServletResponse.setStatus(HttpStatus.OK.value());
            return false;
        }
        return super.preHandle(request, response);
    }

    /**
     * 将非法请求跳转到 /401
     */
    private void response401(ServletResponse response) {
        try {
            HttpServletResponse httpServletResponse = (HttpServletResponse) response;
            httpServletResponse.sendRedirect("/devApi/init/401");
        } catch (IOException e) {
            log.error(e.getMessage());
        }
    }
}
